Controlling system for lifting-magnets.



Riv-1mm) AUG14, 1908; R.I.WRIGHT.

' CONTROLLING SYSTEM FOR LIPTING MAGNETS.

- APPLICATION ITILED APR. 10, 1908.

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ATTORN EV been shunt wound onrT D STAT PAT T nEL'BEX. I, WRIGHT, orcLEvELAND,

To all may concern:

Be it knownthat I, REUBEN I. YVRIGHT, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented or discovered new anduseful Improvements in Controlling Systemsfor Lifting-Magnets, of which the following is a specification.

My invention relates to a new andjmproved system of control forliftingmagnets.

As far as I know, all lifting magnets have and connected directly acrossthe supply mains, or'with'permanent resistances in series with 1 Underthese conditions, the current which flows through the magnet depends onthe resistance of the magnet circuit and the vol-' tage of the mainswhere the magnet is connected. When lifting magnets are attached toeiectric'hoistsor cranes, the voltage of the supply mains at the craneor hoist is at its lowest value just as the magnet is being hoisted awayfrom the pile of maghetioinaterial, on which it is working.

principally'to two causes: First, more current is required to acceleratethe hoisting mechanism, the magnet and the load than is required afterthe load has left the pile; and second, with an excited lifting magnetresting on a pile of magnetic material, the

separate the magnet and its pi e than to hoist the {magnet and loadafter the load has been lifted from thepile. This increased currentcauses an increased drop in e crane and thus a drop of curvoltage at tilrent in the magnet circuit.

I have oliserved that the lifting capacity of a inagnetis roportional-tothe current flowing through ItS WlIKhH and that after a load of magneticmateria has been lifted an" from thedpile, this current may-bemateriaily reduce without causing the magnet to drop its load. It istherefore seen that a shunt magnet has a minimum current through itsshading 'ust at the time that a maximum current is (l esirable and ithas a maximum current when it is desirable to have a minimum current.Such a magnet therefore loses in lifting capacity, and its winding issubjected to greater heating than is desirable.

My invention overcomes these objections and supplies means whereb agreater current may be caused to flow t rough the magtheir wind ingsThis is due a greater pull to' load from the H OHIO, assIeNoR ToTHEELECTRIc CONTROLLER AND SUPPLY COMPANY, OF CLEVELAND,

OHIO, A CORPO RATI\ON QF OHIO.

CONTROLLING SYSTEM FOR LIFT'ING-MAGnn s'.

o' iPatented Aug; 4, .1908. v

Application flle d April 10, 1902. Serial 4 6,207.

1 net winding just as the magnet and load are leaving the pile, andlater to automatically reduce thiscurrentnnd theconsquent unnecessaryheating of the magnet winding.

same load with less heating;

My invention, is illustrated the accompanying sheet of drawin s' whichshows a diagrammatic view thereog -On the drawing, S is a double-poleknife switchwhich connects the motor and magnet circuits to a suitablesource of electrical energy'. From the positive pole of this switchcurrent is led by of the relay 0, from which winding the current passesthrough the motor controller switch C when closed and through the arma-The wire 2 connects the contact I) of the 'magnet controller B to thewire 1 which is connected to the positive side of the switch S.

nected by the wire 3 tothe contact 6 of said cont-roller B, whose arm bcarries the brush 6 arranged to bridge the contacts VI) and b when thecontroller arm I) is swung to the left. I; The arm 8 carries the contact8, which c0 trolled by the winding 0. The contact 0' is connectedthrough the winding 0 and the wire 1 to the positive side if the switchS and thecontact 0 is connected through the winding 8 of the switch S tothe wire 4. The winding s controls the core 3 connected to s and s to beclosed when the winding .9 lifts the said core: I

b. to the left so that brush 1)! spans the conthe magnet winding M asfollows: from the caries.

This allows a magnet to lift a greater load with the same heating ofwindings or the the wire :1 to the winding 0 i ftureA and its field F tothe negative pole of The movable arm sf of the switch S is con--operates with the fixed contact 8', to whiched, the remaining end of themagnet winding and 0 arranged to be bridged by the switchor contacto,which carries a core 0? con-'1' i the switch arm 8 so as to cause thecontacts If the switch B is closed by moving its arm tacts b and b, acircuit is established through "positive side, of the switch S throughthewires 1 and 2, the contacts b, b, and b, the wire 3, the resistanceR, the winding M and the wire 4 to the negative side of the switch S. Inthis circuit the winding M is in series with the resistance R andconnects both across the line. If now thecontroller or switch C isclosed, current is established through the motor circuit as follows:from the positive side of the switch S, through the wire 1, therelay'coil 0, the switch C, the armature A and the field F to thenegative side of the switch S. As stated before, the current through themotor at starting is large. It, therefore, energizes the relay coil 0sufficiently to cause the core '0 to rise so that switch '0 bridges thecontacts 0' and 0, thus establishing a circuit as follows :from thepositive side of the switch S through the wire 1, the coil 0, thecontacts 0, 0 and 0, the coil 3 of the switch S, and the wire 4 to thenegative side of the switch S. This circuit energizes the coil 8 so asto cause it to raise the core 8 and close the contacts 8' and Theclosing of these two contacts shunts the resistance R with the arm .5 ofthe switch S. This shunt permits a larger current to flow through themagnet M, the circuit now being as follows: from the positive side ofthe switch S, through the wire'l, the wire 2, the

contacts b b and b the wire 3, the arm s, the contacts .9 and s, themagnet winding M, and the wire 4 to the negative side of a switch S.

By the proper adjustment of the relay 0, the core 8 may be caused toremain in its upward position until the hoisting motor has lifted themagnet and the load from the pile, and all the moving parts brou ht upto speed. When this has occurred, the current t rough the hoistin motorand the relay coil 0 has gradually decreased until the relay is nolongerable to hold up its core 0. When the core dro s, the circuit of theswitch coil s v of switch is opened at the switch 0 and the arm 8 opensthe contacts s and s, which re-inserts the resistance R in series withthe magnet winding M and decreases the current throu h the magnet, thusreducin its heat ing. if the resistance R is properly proportioned, thecurrent in the winding may be materially reduced without causing themag- ,net to dro any of its load.

When t reload has been transferred to the desired osition, it may bereleased from the ma net ynioving the arm I) of the switch 13 to t eright so that the brush 12 leaves con tact with the contacts 6' and b.

I claim 1. In a controlling system for lifting magnets, an electricmotor, "a lifting -magnet winding in shunt with the motor circuit, andmeans for automaticallyinserting resistance in series with the saidwinding.

2. In a controlling system for lifting magnets, an electric motor, alifting-magnet winding, and means for automatically decreasing thecurrent in the said winding after the said motor has been accelerated.

3. In a controlling system for lifting magnets, an electric motor, alifting magnet winding in shunt with the motor circuit, and meansgoverned by theicnrrent in the motor circuit for automaticallycontrolling the amount of current flowing in the said wind.- ing.

4. In a controlling system for lifting magnets, a lifting-magnetwinding, a resistance in series with said winding, an electro-mags net,contacts controlled by the electro-magnet to shunt said resistance, anelectric motor, a relay winding in the motor circuit, contactscontrolled by the relay winding and controlling said electro-magnet, anda switch to close the circuit of the magnet winding.

5. In a controlling system forlifting 1nag-' nets, a lifting-magnetwinding, a resistance in series with the said winding, an electromagnet,contacts controlled by said electro magnet to shunt the resistance, anelectric motor, a relay winding in the motor circuit, means actuated bysaid relay winding during the rush of current in the motorcircuit be-.

fore the motor has been accelerated to shortcircuit said resistance.

Signed at Cleveland, Ohio, this sixth day of April, A. D. 1908.

REUBEN I. I VRIGHT.

Witnesses: i

C. PmTLE, H. M. DrEMnR.

